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        <div>
            <div><h3 class="title">
                <a name="asio.reference.use_future_t"></a><a class="link" href="use_future_t.html" title="use_future_t">use_future_t</a>
            </h3></div>
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    <p>
        <a class="indexterm" name="asio.indexterm.use_future_t"></a>
    </p>
    <p>
        A completion token type that causes an asynchronous operation to return a
        future.
    </p>
    <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <span class="identifier">Allocator</span> <span class="special">=</span> <span
                class="identifier">std</span><span class="special">::</span><span
                class="identifier">allocator</span><span class="special">&lt;</span><span
                class="keyword">void</span><span class="special">&gt;&gt;</span>
<span class="keyword">class</span> <span class="identifier">use_future_t</span>
</pre>
    <h5>
        <a name="asio.reference.use_future_t.h0"></a>
        <span><a name="asio.reference.use_future_t.types"></a></span><a class="link"
                                                                        href="use_future_t.html#asio.reference.use_future_t.types">Types</a>
    </h5>
    <div class="informaltable">
        <table class="table">
            <colgroup>
                <col>
                <col>
            </colgroup>
            <thead>
            <tr>
                <th>
                    <p>
                        Name
                    </p>
                </th>
                <th>
                    <p>
                        Description
                    </p>
                </th>
            </tr>
            </thead>
            <tbody>
            <tr>
                <td>
                    <p>
                        <a class="link" href="use_future_t/allocator_type.html"
                           title="use_future_t::allocator_type"><span
                                class="bold"><strong>allocator_type</strong></span></a>
                    </p>
                </td>
                <td>
                    <p>
                        The allocator type. The allocator is used when constructing the
                        std::promise object for a given asynchronous operation.
                    </p>
                </td>
            </tr>
            </tbody>
        </table>
    </div>
    <h5>
        <a name="asio.reference.use_future_t.h1"></a>
        <span><a name="asio.reference.use_future_t.member_functions"></a></span><a class="link"
                                                                                   href="use_future_t.html#asio.reference.use_future_t.member_functions">Member
        Functions</a>
    </h5>
    <div class="informaltable">
        <table class="table">
            <colgroup>
                <col>
                <col>
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            <thead>
            <tr>
                <th>
                    <p>
                        Name
                    </p>
                </th>
                <th>
                    <p>
                        Description
                    </p>
                </th>
            </tr>
            </thead>
            <tbody>
            <tr>
                <td>
                    <p>
                        <a class="link" href="use_future_t/get_allocator.html" title="use_future_t::get_allocator"><span
                                class="bold"><strong>get_allocator</strong></span></a>
                    </p>
                </td>
                <td>
                    <p>
                        Obtain allocator.
                    </p>
                </td>
            </tr>
            <tr>
                <td>
                    <p>
                        <a class="link" href="use_future_t/operator_lp__rp_.html" title="use_future_t::operator()"><span
                                class="bold"><strong>operator()</strong></span></a>
                    </p>
                </td>
                <td>
                    <p>
                        Wrap a function object in a packaged task.
                    </p>
                </td>
            </tr>
            <tr>
                <td>
                    <p>
                        <a class="link" href="use_future_t/operator_lb__rb_.html" title="use_future_t::operator[]"><span
                                class="bold"><strong>operator[]</strong></span></a>
                    </p>
                </td>
                <td>
                    <p>
                        (Deprecated: Use rebind().) Specify an alternate allocator.
                    </p>
                </td>
            </tr>
            <tr>
                <td>
                    <p>
                        <a class="link" href="use_future_t/rebind.html" title="use_future_t::rebind"><span class="bold"><strong>rebind</strong></span></a>
                    </p>
                </td>
                <td>
                    <p>
                        Specify an alternate allocator.
                    </p>
                </td>
            </tr>
            <tr>
                <td>
                    <p>
                        <a class="link" href="use_future_t/use_future_t.html" title="use_future_t::use_future_t"><span
                                class="bold"><strong>use_future_t</strong></span></a> <span
                            class="silver">[constructor]</span>
                    </p>
                </td>
                <td>
                    <p>
                        Construct using default-constructed allocator. <br> <span class="silver"> —</span><br> Construct
                        using specified allocator.
                    </p>
                </td>
            </tr>
            </tbody>
        </table>
    </div>
    <p>
        The <a class="link" href="use_future_t.html" title="use_future_t"><code class="computeroutput"><span
            class="identifier">use_future_t</span></code></a>
        class is a completion token type that is used to indicate that an asynchronous
        operation should return a std::future object. A <a class="link" href="use_future_t.html"
                                                           title="use_future_t"><code class="computeroutput"><span
            class="identifier">use_future_t</span></code></a> object may be passed
        as a completion token to an asynchronous operation, typically using the special
        value <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span
            class="identifier">use_future</span></code>. For example:
    </p>
    <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span
            class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span
            class="special">::</span><span class="identifier">size_t</span><span class="special">&gt;</span> <span
            class="identifier">my_future</span>
  <span class="special">=</span> <span class="identifier">my_socket</span><span class="special">.</span><span
                class="identifier">async_read_some</span><span class="special">(</span><span class="identifier">my_buffer</span><span
                class="special">,</span> <span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">use_future</span><span class="special">);</span>
</pre>
    <p>
        The initiating function (async_read_some in the above example) returns a
        future that will receive the result of the operation. If the operation completes
        with an <a class="link" href="error_code.html" title="error_code"><code class="computeroutput"><span
            class="identifier">error_code</span></code></a>
        indicating failure, it is converted into a <a class="link" href="system_error.html" title="system_error"><code
            class="computeroutput"><span class="identifier">system_error</span></code></a> and passed back to
        the caller via the future.
    </p>
    <h5>
        <a name="asio.reference.use_future_t.h2"></a>
        <span><a name="asio.reference.use_future_t.requirements"></a></span><a class="link"
                                                                               href="use_future_t.html#asio.reference.use_future_t.requirements">Requirements</a>
    </h5>
    <p>
        <span class="emphasis"><em>Header: </em></span><code class="literal">asio/use_future.hpp</code>
    </p>
    <p>
        <span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
    </p>
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            <div class="copyright-footer">Copyright © 2003-2022 Christopher M. Kohlhoff<p>
                Distributed under the Boost Software License, Version 1.0. (See accompanying
                file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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